Mill production method and layout



M r 1932. w. WORTHINGTON MILL PRODUCTION METHOD AND LAYOUT Filed Dec.13. 1929 Patented Mar. 29, 1932 PATENT OFFICE WARREN WORTHINGTON, OFPITTSBURGH, PENNSYLVANIA MILL PRODUCTION METHOD AND LAYOUT Applicationfiled December 13, 1929. Serial No. 413,878.

made to overcome certain of those which seem to be the most outstanding.But, previous to the present inventiomthe steel and like, al-

lied industries have been working under a handicap.

This handicap arises from the fact that although it is well known to theindustrythat the products of the present sheet mill methods arenot theefficient summation of work, labor, material, and treatment involved,yet no one has been able to determine a factor, which, if met, wouldallow the production of a higher quality finished product, and do so ata greatly increased overall efficiency.

" As explained above the problemswhich arise in the steel and alliedindustries are many and complex. The ehiciency of methods and layoutsemployed isordinarilyevidenced by the high cost of production, thenumber of rejected pieces, or the quality of the finished product; but,until the present invention, it was not traced to lack of flexibility orlack of cooperative independence between units 9 producing sheets andplates of varied characteristics, especially where those sheets havecertain characteristics in common with those produced by adjacent units,for instance, sheets or plates of the same width, gauge, or

' of-the same grade of steel.

A common measure of rolling mill difficulties is scaled on theproportion of time lost during the operation of the mill; that is, theseriousness of a ditficulty is estimated in proportion to the delay itcauses in the operation of the mill, rather than in the loss of a smallamount of material or of a part of the mill itself. Thus, the solutionof the proby lem which arises out of shutdowns and the resultant evileffects is all important to the industry. Spare motors, engines, and thesubstitution of new parts, rather than repairing the old, are examplesof how far the industry is willing to go in order to lessen prow ductiondelays and mixups.

A layout, such as now commonly em loyed in steel mill practice consistsof a plura ity of mills, each mill having a cooperating heating furnaceand being transversely located wit-h respect to the other mills.Continuous conveyors are sometimes positioned between adjacent mills andare connected between the rolls of one mill and the furnace of anothermill. It can be readily conceived just what effect the breaking of apart in one mill or the need 'of replacement of the rolls of anothermill will have upon production of the entire layout. The formingoperation for sheets of a given gauge is essentially a series ofcooperative steps in which each unit involved, is absolutely dependentupon other units for its supply of partly finished sheets; thus, ashutdown of any unit involved in the operations will upset the entireconformity'of pro,-' duction layout. For these reasons an unusu- '7 allylarge demand for one particular gauge of sheet-will also causedifficulties. It is often necessary to shut down anumber of units undersuch a condition of production, and this of course cuts down productionefiiciency.

Another disadvantage in the present mill layout rests upon the number ofhigh priced men that must be employed in order; that the variousapparatus may be efiectively operated. Since the heating furnaces ofeach .80 traverse layout are directly opposite each other, a veritableinferno is created, reducing the number of working hours for each manand, of course, increasing the wage scale.

Due to the interdependence of the units of present day mill layouts, themills of each unit cannot be varied as to speed with respect to adjacentunits. Speed variation is desirable in order to meet the requirements ofdifferent thicknesses, grades, quality, and quantity of sheeting. Thentoo, the control of speed is desirable in order to obtain the requisiteflexibility where various rolling temperatures are necessary or areemploycd, and also because of the variation in r the number of passes,and the reduction necessary in the pass of each unit. At first glance itwould seem that the temperature of the sheets or plates being passedthrough one unit of'a plurality of speed dependent units could beindependently varied. But, this is not wholly true, for, there is atemperature corresponding to a given speed that will produce mostefficient results. This can be visualized, since with an increase ofspeed there will be an increase of frictional heat generated, and sincethe time consumed in the passes effects the heat loss therein, andfrictional heating efiects are further increased with an increase ofthickness reduction in a given pass. Then too, it is common in theindustry to have an unexpected demand for certain gauge sheets, and aconsequent lesser demand for other gauge sheets.

And it has been one object of this invention to disc-over a factor whichwill eliminate the cause of a large proportion of the inefliciencies ofpresent day rolling methods, and to provide a solution for this cause.

Another object of this invention has been to provide a production millmethod and layout whereby the heat and speed of the sheets passingthrough, the rolls of adjacent mills can be independently controlled inrespect to other mill units.

Another object of this invention has been to provide a production methodand layout whereby the heating furnace of each of the adjacent unitswill be separated from other furnaces by the length of the rolling, orof the rolling and shearing apparatus.

A further object of this invention has been to provide a productionlayout, each unit of which can be made to continuously operate andproduce a quantity of sheets or the like proportionate to the demand fora given ,size without lessening the quantity of production of other sizesheets.

A further object of this invention has been to provide a mill productionmethod whereby each unit thereof will have cooperative independence.

Other objects of this invention will appear to those skilled in the artfrom the following description taken in conjunction with theaccompanying drawing, in which:

The figure is a plan view of a sheet production layout arranged inaccordance with one embodiment of this invention.

In the drawing, a preferred form of production layout is shownthatgcomprises a plurality of longitudinally spaced sheets and platemetal working units A, B, C, D, and E, which may be enclosed within theconfines of the shop area 9.

In order that sheets of desired gauge may be attained, each of the firstthree of said units A, B, and C is adapted for a hot rolling process.The first of these units A, is provided with a suitable heating furnace11 in order that breakdown. plates, or the like,

may be prepared for rolling. The furnace 11, has a conveyor type feedtable 12 adjoining one end and a discharge table 13 adjoining the otherend thereof.

For purposes of illustration, the sheets- To reduce breakdown plates orthe like, to

sheets of suitable size, say 20 gauge, a rolling mill 14 is providedwhich may be operated as 2-high, but will preferably be operated as3-high. Power for rotating rollers of the mill 14, is obtained through asuitable speed reduction mechanism 16 from a motor 17. Both this motorand thegear mechanism are located in the individual compartment 18. Themotor may be, and preferably is a variable speed motor.

In order that plates from the heating furnace 11 will be continuousl fedto the mill 14, and that completely rolle sheets will be fed to ashearing mechanism 20, roll tables 19 and 21 are provided.

' The breakdown plates on being heated in the furnace 11 and rolled inthe mill 14, are formed into sheets of, say 20 gauge. These 20 gaugesheets are now ready for shearing and are conveyed on the discharge rolltable 19 to the shear 20, where they may be cut in two or more piecesand discharged upon a shear table 21. Thence, the sheets are stacked orplaced in stock in the area 22, located opposite the space between unitsA and B, for

cooling, resting, and/or curing.

If sheets of lesser thickness, say 26 gau are required, the 20 gaugesheets from t e stock area 22 are carried by a suitable overhead crane'Xpositioned above the formation of units-on line therewith to a feedtable 25 of a heating furnace 26 of unit B. After a proper heatingtemperature of the sheets has been attained, they are conveyed from theroll table 27 to the mill 28 and rolled into 26 gauge sheets. If sheetsof the gauges re-' ferred as examples, are to be rolled in this unit B,four or six sheets may be worked together, by the usual stackingprocedure The mill 28, preferably of the two-high type, has a suitablemotivating mechanism designated in its entirety by 29, similar to 16, 17of unit A. As in unit A, the sheets are now stacked in a stock area 30for cooling, in effect curing, resting and/or storage purposes.

In order that those sln'lled in the art may more readily understand justwhy I cool and/or rest the metal sheets after one working operation andbefore another, a brief explanation will follow. Although resting isgenerally known to the metal working indus try, yet many of the resultstherefrom and the value thereof, are not generally known. The tensilestrength and the elastic limit of iron that has been distorted beyondits elastic limit will increase for a long time, probably for manyyears. Further, internal is first heated, then hot worked, cooled, and

stresses induced by irregular cooling or by cold working may begradually relieved by rest, to the benefit of the metal, especially ifsolutely constant efl'ecton the elastic limit of most metals.

The thermo-electric power that is thought to be the true index ofstress, changes rapidly when steel has a heat of about 66 G. Since thetemperature of a stack of sheets may approximate this value, it is feltthat this is one of the possible explanations of the benefits derivedfrom resting. And, since the metal finally rested before the operationis again repeated, I have produced a remarkably better-product by mymethod simply through the agency of resting.

Further, the cooling in itself has a very excellent effect upon thequality ofthe product.

Tempering, taken in its general sense, is accomplished thereby aftereach hot working or rolling of the product. The crystalline structure isbetter and morethoroughly reduced and refined, and is given morehomogeneity; segregation and heterogeneousness are more thoroughlybroken up, and the strength of the metal-is ultimately increased. But, Ihave added these two methods together, namely, cooling and resting, andby the combination thereof have further increased the quality of theproduct.

sequent reworking.

The length of time of the rest will depend upon the particular nature ofthe metal, and in some cases the short resting accomplished by merecooling may be sufficient.

Since a large number of sheets are normally piled or stacked in a givenstock area, not

of six or eight sheets of 26 gauge may be hot rolled at one time in unitC. The unit C may have rolls and suitable heating furnaces somewhatsimilar to unit B and, of course, the working process of the sheets iscarried on in the same manner. After the sheets have been rolled into 30gauge thickness, they are placed in the stock area 38. As shown in thedrawing, parallel, and, transversely opposite to this unit C, a unit Cmay be installed to meet future requirements. This unit C is illustratedto bring out the possibility of the addition. of parallel units to anyor all of the three hot rolling units A, B, and C in order to meetfuture demands or excessive demands for a given gauge sheet. As seen,the so-called future units may be driven by a power shaft common to itsadj acent parallel units or common to those units which have a givenwork in common. Unit Chas a motivating unit and mechanism 37 similar tothat of units A and B.

Any or all of the sheets from the units A, B, C, etc., are trimmed andsheared to length and width in the unit D having a trimmer 40 and ashear 42, and suitable sheet conveyingtables 41, 43 and 44. Afterpassing through this unit D, the sheets may be placed in stock. If it isdesirable to cold roll the sheets in order to increase their hardnessand improve their surface, they may be run singularly through one oranother of the three parallel roll stands 46 of unit E. A motor 47 andits speed reduction gear 48, located in the space 49, furnish power fordriving these roll stands. After cold rolling the sheets are ready forannealing and may be subsequently stored or galvanized as desired.

The layout shown as an embodiment of my.

only are the sheets given an opportunity for inventiomis adapted to meetthe demands for rest, but also, are somewhat or mildly annealed duringthatperiod by reason of the heat held in by the large quantityof metalpresent and the continual adding of new sheets just after the hotrolling operations. The applicant stacks the newly added sheets so thatthey will impart heat to the old sheets, and so that in addition, theold or rest-treated sheets can readily be first removed for a sub Thisexplanation has merely been added to more clearly show just how theoperation is conducted during the resting period. That is, by thisstacking method the value of the resting period is greatly enhancedsince a very slight heat is maintained atall times. As a result, acombined annealing and resting action is produced upon the sheetsthereby very materially increasing their strength and grainqualidifferent size sheets, and it is also apparent that a temporaryshutdown of one hot rolling unit will not affect or delay the operationof other units. Sheets from stock areas 22, 30, and 38 can be shearedand trimmed and if desired cold rolled and annealed to meet the demandsof those sizes. If there is a greater demand, for instance, for 26 gaugesheets, and for 30 gauge sheets, then parallel units may be added to thehot rolling units A and B, in a manner similar to that shown for unit .0in the form of unit 0'.

Each hot rolling unit, although its operation is independently andseparately controlled in respect to other longitudinally spaced unitscan be cooperatively and semi: dependently operated withrespect to adacent and non-adjacent units. The advantages derived from the provisionof a plurality of longitudinally-spaced, independent, cooperative'units, is at once apparent. -First, each unit, effecting a certaintreatment of the sheets or plates, is set off by itself.

Thus, the rollfspeed, the temperature of too,

the material being treated, and the thickness reduction between thepasses of each unit may be entirely independently controlled in respectto an adjacent unit. A substantially straight-line spaced-longitudinalpositioning or formation of each unit not only adds to the efiiciency ofthe entire layout, but also permits efiicient independentce of theadjacent, unit, and has the additional advantage that the partiallyfinished sheets are in effect cured or aged in thevarious storagespaces.

Confusion is eliminated, and future demands for given size sheets arereadily taken care of by adding additional units of similar purpose intransverse and parallel positioning with respect to the original unit.Then a saving in power may be effected by axling future mills to the oldmills as shown in connection with units C and C. The stock areas 22, 30,and 38 have been located opposite the space between adjacent units so asto permit the sheet stacking and charging crews to operate efficiently;and, if desired, a conveyor may be installed between units to meet thedemands of a given situav tion. This layout is productive of quickrepairs, for the men are given more room in which to work, and the partsare more readily accessible.

One of the great advantages of the layout lies in the fact that thesheetsor other products of production will always move in the samedirection, no matter What their size or gauge, degree or nature oftreatment. In other words. the crane X when carrying sheets or platesneed only travel from left to right in the layout shown in the drawing.saving in time, labor, and expense that arise from mixups andcomplicatedsituations, will necessarily follow.

While I have described but one embodiment ofthis invention, it will beapparent that many changes, modifications, substitutions, additions, andomissions, or combinations thereof may be made in this device withoutdeparting from the spirit and scope of the invention as indicated in theappended claims.

What I claim as new and desire'to secure byLetters Patent is: i

1. Amill layout which includes a plurality of metal-working unitspositioned in substantially straight-line spaced longitudinal formation;the first of said units including a heating furnace, a mill, a rolltable located between said furnace and said mill, a shear,

a roll table located between said mill and said shear; the second ofsaid units including a heating furnace, a mill, and a roll table betweensaid furnace and said mill; the third of said units including afurnace,a mill and a roll table between said mill and said furnace;

each of said three units having an individual v sheet stacking area nearits discharge end;

the fourth of said units including a trimmer furnace plurality and shearhaving a table therebetween; and, the fifth of said units including aplurality of transversely positioned cold rolls.

' 2. A mill layout which includes a plurality of metal-working unitspositioned in substantially straight-line spaced-longitudinalformation"; the first of said units including a heating furnace, hotrolls and a conveyor table therebetween, a shear and a conveyor tablebetween said rolls and said shear; the second of said units including aheating furnace, a mill and a roll table between said furnace and saidmill; the third of said units including a furnace, a mill and a rolltable between said mill and said furnace; each of said three unitshaving an individual storage area. opposite each space between units,and having suitable motivating mechanisms; the fourth of said unitsincluding a trimmer and a shear having a conveyor table therebetween;the fifth of said units including a alurality of transversely aXled coldrolls, said rolls being adapted to be driven by a single motivatingmechanism.

3. A mill layout which includes a plurality of metal-working unitspositioned in substantially straight-line spaced-longitudinal formation;the first of said units including a heating furnace, a mill, a rolltable located between said furnace and said mill, a shear, and arolltable between said mill and said shear; the second of said unitsincluding a heating furnace, a mill and a roll table located betweensaid furnace and said mill; the third of said units including a furnace,a mill and a conveyor table therebetween, the Whole being constructedand arranged to permit a plurality of like units to be transverselypositioned adjacent each other.

4:. A mill layout which includes a plurality of metal working unitspositioned in substantially straight-line spaced-longitudinal formation:the first of said units including a heating furnace, a mill, a rolltable located between said furnace and said mill, a shear, a roll tablebetween said mill and said shear; the second of said units including aheating-furnace, a mill and a roll table between said furnace and saidmill; the third of said units including a furnace, a roll table and aconveyor table therebetween, the whole being constructed and arranged topermit a of similar units to be transversely positioned adjacent eachother; each of said three units having an individual stock area near itsdischarge end; the fourth of said units including a trimmer and shearhaving a table therebetween; and the fifth of said units including aplurality of transversely positioned cold rolls. v

5. A mill layout which includes a plurality'of metal working unitspositioned in substantially straight-line spaced-longitudinal formation;the first of said units including a heating furnace, a mill, a shear,and suitable tables therefor; the second of said units ineluding aheating furnace, a mill, and suitable tables therefor; the third of saidunits including a furnace, a mill, and suitable tables therefor; each ofsaid three units having an individual sheet stacking area near itsdischarge end; the fourth of said units in-- cluding a trimmer and ashear having a suitable table therebetween.

6. A mill layout which includes a plurality of metal working unitspositioned in substantially straight-line spaced-longitudinal formation;the first of said units including a heating furnace, a mill, a rolltable located between said furnace and said mill, a shear, and rolltable located between said mill and said shear; the second of said unitsincluding a heating furnace, a mill, and a roll table between saidfurnace and said mill; the third of said units including a furnace, amill, and a roll table between said mill and said furnace; each of saidthree units having an individual sheet stacking area near its dischargeend, each of said areas having a trans- 7 each of said three unitshaving an individual second of said units including a trimmer, a

sheet stacking area near its discharge end, the length of said areacorresponding to the spacing between each adjacent unit; and the fourthof said units including a cold roll.

8. A mill layout which includes a plurality of metal working unitspositionedin substantially straight-line spaced-longitudinal formation;the first of said units including a feed table, a heatin furnace, adischarge table, a mill, a roll ta le, a shear, and a shear table; thesecond 0f sa1d units including a feed table, a heating furnace, a rolltable, and a mill; each of said units having an individual sheetstacking area near its discharge end and the length thereofcorresponding substantially to the spacing between said units; and athird unit including a plurality of transversely positioned cold rolls.

9. A 'mill layout which includes a plurality of metal working unitspositioned in substantialy straight-line spaced-longitudinal formation;the first of said units including a feed table, a heating furnace, adischarge table, a mill, a roll table, a shear, and

a shear table in the order mentioned; the

shear, and a suitable table therebetwen; each of said two units havingan individual sheet stacking area near its discharge end whose lengthcorresponds to the spacing between adjacent units; and a third of saidunits including a plurality of transversely positioned cold rolls.

10. A mill layout which includes a plurality of metal working unitspositioned in substantially straight-line spaced-longitudinal formation;the first of said units including a heating furnace, hot rolls, a shear,and suitable conveyor feed and discharge tables therefor; the second ofsaid units including a heating furnace, a plurality of transverselypositioned mills, and suitable tables therefor, the third of said unitsincluding a trimmer, a shear, and suitable tables therefor; the fourthof said units including a plurality of transversely positioned coldrolls provided with a common motivatiliguniu 11. In a mill layout whichincludes a pluv rality of metal working units positioned insubstantially straight-line and spaced-longitudinal formation; the firstof said units including a heating furnace, a mill, a roll table locatedbetween said furnace and said mill, a

shear and a roll table between said mill and said shear; the second ofsaid units including a heating furnace, a mill, and a roll table betweensaid furnace and said mill; the third of said units including a furnace,a roll table and a conveyor therebetween, the whole being constructedand arranged to permit a plurality of similar u'nits'to be transverselypositioned with respect to each other and to be motivated by a commonmechanism; each of said three units having an individual sheet stackingarea near its discharge end whose length corresponds to the stackingbetween adjacent of said units the fourth of said un1ts includingattrimmer and a shear, and suitable tables therefor; the fifth of saidunits including suitable cold rolls; and a conveying mechanism disposedabove and on line with said metal working units for carrying metal toand from said units as well as to and from said stacking areas.

In testimony whereof, I have hereunto subscribed my name this 11th dayof December, 1929.

WARREN WORTHINGTON.

